Kiln cars

ABSTRACT

A low thermal mass kiln car having a wheeled base on which is superposed a thermal barrier means composed of layers of lightweight non-load-bearing thermally insulating material, and a plurality of posts supported from the base of the kiln car and projecting upwardly through the thermal barrier means, the posts being supported with lateral stability by sockets on the base and carrying an upper deck for supporting the ware.

United States Patent [191 6/1934 lpsen et al. 263/28 Barsby Sept. 18, 1973 54 KILN CARS 3,168,299 2/l965 Miller 263/28 [751 Invent gg gz gi f i wwmhampmn, FOREIGN PATENTS OR APPLICATIONS g g 433,497 8/1935 Great Britain 25/142 B [73] Assignee: Gibbons Brothers Limited, Brierley 528,651 5/1954 Belgium 263/28 Hill, Stafford, England [22] Filed: Jan. 20, 1972 lfrimqry Examiner-1ohn J. Camb I h Aitorney-Paul BEgdon, Edward-F. Welsh, William 1 I 239503 o. Kratz, and Richard v.- Westerhoff.

[30] Foreign Application Priority Data WMWMW p m p g Jan. 28, 1 971 Great Britain 3,412/71 ABSTRACT [52] U 8 Cl 432/241 A low thermal mass kiln car having a wheeled base on I 51 11 9/26 which is superposed a thermal barrier means composed [58] i 25/142 B of layers of light-weight non-load-bearing thermally in- I 25/142 sulating material, and a plurality of posts supported from the base of the kiln car and projecting upwardly [56] Reeren-ces Cited through the thermal barrier means, the posts being supported with lateral stability by sockets on the base and UNITED STATES PATENTS carrying an upper deck for supporting the ware.

14 Claims, Drawing Figures PATENTEDSEPIBIHB 3.759.661

SHEET 2 [1F 4 I PATENTEUSEPI 8l973 SHEET 3 UP 4 FIG .4.

[lull/l4 PATENT sun 81973 KIILN (3 BACKGROUND OF'TI-IE INVENTION 1. Field of the Invention This invention relates to travelling supports ordinarily known and herein termed kiln cars which are movable through a kiln or like heated enclosure and, in use, serve to support respective loads of ceramic ware required to undergo heating in the kiln or enclosure.

The invention concerns kiln cars each of which comprises a base having wheels enabling same to travel along a track in the kiln or enclosure, and superposed on the base a structure known generally and herein termed a car top, on the upwardly presented face of which the load of ceramic. were is supported when'the kiln car is in use. Such kiln cars are herein referred to .as being of the kind specified.

2. Description of the Prior Art In conventional constructions of kiln car of the kind specified the car top comprises a lower part or subdeck which serves the purpose of acting as a heat barrier between a heating zone in which the were is situated,

- when the kiln car is in use, and the base of the kiln car,

with the object of maintaining satisfactory environmental conditions for the relatively moving parts of the kiln car, that isto say the'wheels, bearings and so'forth, as

well as enabling the base of the kiln carto be constructed of ordinary mild steel girders or the like strucrial which serve peripherally to enclose a central portion formed of cast ceramic material. In some cases the central portion may include a layer of loose aggregate.

The upper part of the car top is usually composed of beams, termed piers, laid side by side on the upwardly presented surface of the subdeck, and at their upper ends collectively providing the required supporting surface for the ware. Often there is more than one layer of such piers, the piers of successive layers being ar-' ranged transversely to each other. In some cases the upper part of the car top has been composed of relatively thick-walled posts having enlargements of their cross-section at their lower and upper ends standing on but not penetrating the subdeck these posts supporting a were carrying platform respectively.

Alternatively it has been proposed in a kiln car of the kind specified to provide a subdeck composed of a metal box containing foil. The upper part of the car top in this case comprised a number of upwardly extending posts standing, at their lower ends on the box forming the subdeck and carrying at their upper ends a load carrying deck for supporting the ware.

These constructions, however, suffer from a number of disadvantages.

One of the major disadvantages is that a considerable weight of material is involved in the construction or formation of the car top as a whole (i.e., the subdeck and upper part), and inevitably the heat absorbed-by that, or larger than that, absorbed by the load of ceramic ware.

In fast firing cycles where typically the ware may have a residence time in the kiln or enclosure of the order of 1 hour, heating of the ware to the proper temperature may be delayed, and, moreover, a very substantial quantity of heat is lost when the car moves out of theenclosure and the heat absorbed by the car top is dissipated.

SUMMARY OF THE INVENTION The object of the present invention is to provide a new or improved construction of kiln car whereby these disadvantages are avoided or reduced.

According to the invention we provide a kiln car comprising a base having wheels enabling the car to travel along a track in a kiln or enclosure, and a car top superposed on the base and which includes firstly a load carrying means formed of posts having lower end portions interengaged vertically with complementary "receiving elements on the base and providing stable support for the posts, the latter at their upper endssupporting an upper deck for carrying the ware, and secondly a thermal barrier means through which the posts extend.

The interengagement of the posts, directly with the base of the kiln can provide the required lateral stability for theposts upper deck and ware carried thereby. Thus the thermal barrier means may be composed of layers of lightweight material since it performs only the function of heat-insulation and does not require to either bear anypart of the load or provide stabilization the car top is substantial and may be comparable'with therefor. This enables the mass 'ofmaterial incorporated in the car top to be very significantly reduced in comparison with conventional car tops. Accordingly the car top in accordance with the invention is especially suitable for use in kilncars requiredto undergo fast heating cycles as above referred to.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying drawings wherein:

FIG. 1 is a view in side elevation and in longitudinal cross-section on the line 22 of FIG. 2 through one embodiment of kiln car in accordance with the invention;

FIG. 2 is a view in transverse cross-section on theline 1-1- of FIG. 1 through'the same embodiment;

FIG. 3 is a plan view of the same embodiment in which the top deck is omitted;

FIG. 4 is a fragmentary view on an enlarged scale in vertical longitudinal cross-section through two adjacent kiln cars;

FIG. 5 is a fragmentary view in plan showing a modified form of top layer in the heat insulating barrier; and

FIG. 6 is a fragmentary plan view on an enlarged scale of the top deck of the kiln car.

DESCRIPTION OF THE PREFERRED EMBODIMENTS superposed a set of transversely extending longitudi-,-

nally spaced girders I2 welded to the girders II. The

resulting grid is surrounded by an outer frame composed of longitudinally extending girders 13 and transverse girders 14.

Axle beams 15 carrying flanged wheels 16 for running on rails extending through the kiln with which the car is intended to be used are supported by brackets 17 secured to certain of the girders 11.

All these components may be made from relatively inexpensive material, for example mild steel.

When the kiln car is in use, the load of ware is supported by a car top comprising an upper deck 19. Such deck is composed of a plurality of rectangular thin walled plates or bats 20 of ceramic material formed with bevelled corners to form apertures so that collectively they are supported in coplanar relation and located against horizontal displacement by caps 21 having upwardly projecting square spigots 22 extending through the apertures defined by the cut-outs, as seen more particularly in FIG. 6.

The car top further comprises a plurality of upwardly sockets 24 or secured thereto as by welding if desired. The barrier means is composed of a plurality of strata or layers of which the uppermost is a thin plate of ceramic batt or compressed fibre board tiles 26. This typically has a thickness of only some quarter of an inch and hence is of very low mass per unit area. The tiles 26 as seen in FIG. 3 are bevelled at their corners to provide apertures for passage of the posts. Where the posts emerge they are fitted with frustoconical sleeves 26a closely embracing the posts and covering the apertures. Two types of tiles are involved projecting support elements in the form of thin walled posts of circular cross-section composed of ceramic materials as indicated at 23. The wall thickness of the tubes is selected to provide adequate strength to carry the load, whilst at the same time restricting the heat conduction path from the zone 18 to the base of the car, and thereby reducing the rate of transference of heat to the base of the car. The tubes may have a diameter of between 2.5 cm and 10 cm typically about 5 cm, and a wall thickness of between 3 mm and 25 mm respectively typically about 6 mm.

These dimensions correspond to a ratio of crosssectional area to circumscribing area of 0.42. This may be varied in a range 0.3 to 0.8 while still preserving the required restriction as to heat conduction and also the required strength.

Posts of other cross-sectional shape may be employed e.g., cruciform shape or hollow rectangular shape. In such cases the ratio of cross-sectional area to circumscribing area would preferably be in the range already mentioned. I

At their lower ends the posts interfit vertically with complementary elements in a male and female relation such as to provide lateral stability to the posts. Thus in one form the necessary elements comprise sockets 24 on the base of the car. Such sockets may be formed from mild steel sheet or plate welded to appropriate H girders such as the girders 12.

The lower end portions of the posts 23 are a relatively loose sliding fit in the sockets 24, thereby providing an air space between the inner surfaces of the'sockets and the tubes except for points of local contact, and further retarding conductive heat transmission from the tubes to the base of the car.

It will be noted that the posts are removable from the sockets and, therefore, the number of posts employed can be varied as required in accordance with the load to be carried. Further, any damaged posts can readily be replaced.

Overlying the base of the car, and situated at a level just above the base, is a thermal barrier means 25 having apertures through which the posts 23 extend. The barrier means is, therefore, not structurally loaded by the posts and does not perform any load-bearing function with respect to the load of ware or the parts of the car top above the barrier means. The barrier means is supported in metal plates 28 on the upper ends of the in the layer shown in FIG. 3, whereas in the modification shown in FIG. 5 a single form of tile 26b is used having an additional V-shaped cut-out 260 along each edge.

Below the tiles 26 are three layers of different materials selected to withstand the temperature conditions. The first layer 27a may be composed of a aluminosilicate ceramic fibre the material known as KOOWOOL is suitable. This material is of fairly open or uncompressed forrn. The interstices between the fibres provide a particularly effective degree of heat insulation. Blocks of rigid ceramic heat insulating material 27b are provided in the layer 27a to support the tiles 26. The second layer 27c is composed of Vermiculite and is of particulate form. The third layer 27d is composed of a board or tiles of light-weight slab material such as calcium silicate. Alternatively a diatomaceous material such as that known as SKAMOL N/4 is suitable.

Ifdesired the particulate layer 270 can be replaced by one composed of a light weight heat insulating or other material of non-particulate i.e., shape holding form. This allows posts 23 to be withdrawn for replacement without spillage material into the openings through the barrier means or into the sockets 24.

The barrier means further includes a peripheral frame composed along the sides of insulating refractory bricks 29 and plates 30 supported on the peripheral girders 13 and 14 of the base.

At one end of the car the girder 14 carries an insulating refractory brick 31 the end face of which has an upwardly presented step 32, in profile whereas the other end of the car of the brick 33 has an end face which has a downwardly presented step 34 in profile. The ends of the girders l1 carry contact plates 35 which engage to preserve a stepped passageway between stepped profile faces of the bricks 31 33 on two successive cars when their plates 35 abut one another.

For a kiln car having typical plan dimensions of about 6 feet (1.83 m) by 8 feet (2.44 m) the overall mass of the car top, that is to say the upper deck 19, posts 23 and barrier means 25 compared with that of a conventional car top is contrasted in the table below.

Low Thermal Mass Kiln Car according to the invention Conventional Kiln Car (total 2) The highly advantageous reduction in mass and consequent reduction in heat absorbed from the kiln is brought about by employing the higher density thermal insulating material sparingly e.g.,- in relatively thin layers and sections such as plates 26 and posts 23. The required mechanical strength and stability is maintained tance to flame erosion at its upper surface, and

bounded laterally by dense elements of considerable mechanical strength, yet in its interior the barrier means is composed of relatively light materials.

In consequence this material absorbs only a relatively small quantity of heat in comparison with car tops of conventional form and the kiln car, is, therefore, especially well adapted for use kilns or other enclosures where heating is requiredto be carried out in accor-v dance .with a short cycle time. In the embodiment described the mass per unit plan area presented by the layers 26, 27a 27b 27c is of the order of 0.005 Kg/sq cm (approximately lb./sq.ft/). Somewhat more dense heat insulating materials could be employed providing a mass per unit plan area of up to 0.010 Kg/sq. cm (approximately lb./sq,ft) while still maintaining the technical advantages achieved by the present invention.

I claim: r v 1. In a kiln'car comprising a base having wheels for running on a kiln track, a car top superposed on the base, a non-load bearing thermal barrier means overlying the base, upright supports extending through said thermal barrier means, and an upper ware supporting deck carried by said supports, the improvement wherein:

a. the supports comprise thin-walled support elements of non-metallic material;

b. receiving elements for the support elements are disposed at least predominantly below, and thermally protected by said thermal barrier means; and

c. the support elements interfit vertically with the receiving elements.

2. A kiln car according to claim 1, wherein said support elements releasably interfit withthe corresponding receiving elements.

3. A kiln car according to claim 2, whereinsaid receiving elements comprise sockets and the support elements comprise hollow posts, and wherein the lower ends of the posts are loosely interfitted with said sockets to minimise heat transference between the posts and the sockets.

4. A kiln car according to claim 3 wherein said thermal barrier means rests on metal plates extending between and resting onor connected to said sockets adjacent to their upper ends.

5. A kiln car according to claim 4 wherein said base comprises superposed sets of spaced parallel beams, at

, least one set thereof extending between and connecting said sockets with each other. v

' 6. A kiln car according to claim 1 wherein at each v end said car top incorporates:

a. non-metallic refractory elements having end faces of complementary stepped profile in vertical longitudinal cross-section.

b. abutment members adapted to engage the corresponding abutment members on an adjacent car to maintain separation between complementary ones of said end faces on adjacent cars respectively and hence maintain a passageway of stepped profile between said adjacent cars.

7. A kiln car according to claim 1 wherein said barrier means is composed at its upper and lateral boundaries of relatively dense plate like elements providing protection against and able to withstand environmental conditions at these localities in the kiln and an interior composed of less dense heat insulating material.

8. A kiln car according to claim 1 wherein the mass per unit area in plan of a main central portion of said thermalbarrier means excluding peripherally extending elements thereof does not substantially exceed 0.010 Kg/sq. centimetre.

9. A kiln car according to claim 1 wherein each support element is a hollow post the dimensions of which are such that the ratio of its transverse cross-sectional area relative to its circumscribed area is between 0.3 and 0.8, to reduce conductive transmission of the heat to said base of said kiln car to an acceptably low level while providing the required mechanical strength to support the ware load. 7

10. A kiln car according to claim 9 wherein said barrier means is composed of a material which is shape holding around apertures through which said posts extend.

11. A kiln car according to claim 1, wherein the thermal barrier means includes an upper plate-like layer which is resistant to flame impingement.

12. A kiln car according to claim '11, wherein the thermal barrier means includes ceramic supports.

13. A kiln car according to claim 1, wherein the support elements comprise hollow posts, including sleeves provided on said posts and arranged to surround apertures in the thermal barrier means through which said posts extend.

14. A kiln car according to claim ll, wherein the thermal barrier means comprises a plurality of layers of thermal insulation material.

I i il 4* i i 

1. In a kiln car comprising a base having wheels for running on a kiln track, a car top superposed on the base, a non-load bearing thermal barrier means overlying the base, upright supports extending through said thermal barrier means, and an upper ware supporting deck carried by said supports, the improvement wherein: a. the supports comprise thin-walled support elements of nonmetallic material; b. receiving elements for the support elements are disposed at least predominantly below, and thermally protected by said thermal barrier means; and c. the support elements interfit vertically with the receiving elements.
 2. A kiln car according to claim 1, wherein said support elements releasably interfit with the corresponding receiving elements.
 3. A kiln car according to claim 2, wherein said receiving elements comprise sockets and the support elements comprise hollow posts, and wherein the lower ends of the posts are loosely interfitted with said sockets to minimise heat transference between the posts and the sockets.
 4. A kiln car according to claim 3 wherein said thermal barrier means rests on metal plates extending between and resting on or connected to said sockets adjacent to their upper ends.
 5. A kiln car according to claim 4 wherein said base comprises superposed sets of spaced parallel beams, at least one set thereof extending between and connecting said sockets with each other.
 6. A kiln car according to claim 1 wherein at each end said car top incorporates: a. non-metallic refractory elements having end faces of complementary stepped profile in vertical longitudinal cross-section. b. abutment members adapted to engage the corresponding abutment members on an adjacent car to maintain separation between complementary ones of said end faces on adjacent cars respectively and hence maintain a passageway of stepped profile between said adjacent cars.
 7. A kiln car according to claim 1 wherein said barrier means is composed at its upper and lateral boundaries of relatively dense plate like elements providing protection against and able to withstand environmental conditions at these localities in the kiln and an interior composed of less dense heat insulating material.
 8. A kiln car according to claim 1 wherein the mass per unit area in plan of a main central portion of said thermal barrier means excluding peripherally extending elements thereof does not substantially exceed 0.010 Kg/sq. centimetre.
 9. A kiln car according to claim 1 wherein each support element is a hollow post the dimensions of which are such that the ratio of its transverse cross-sectional area relative to its circumscribed area is between 0.3 and 0.8, to reduce conductive transmission of the heat to said base of said kiln car to an acceptably low level while providing the required mechanical strength to support the ware load.
 10. A kiln car according to claim 9 wherein said barrier means is composed of a material which is shape holding around apertures through which said posts extend.
 11. A kiln car according to claim 1, wherein the thermal barrier means includes an upper plate-like layer which is resistant to flame impingement.
 12. A kiln car according to claim 11, wherein the thermal barrier means includes ceramic supports.
 13. A kiln car according to claim 1, wherein the support elements comprise hollow posts, including sleeves provided on said posts and arranged to surround apertures in the thermal barrier means through which said posts extend.
 14. A kiln car according to claim 1, wherein the thermal barrier means comprises a plurality of layers of thermal insulation material. 